I wanted to create an ICT to check for shorts and validate some of the voltage levels on a PCB that I created, using a jig. I have placed probe points on the desired nets and will be using pogo pins on a jig to test the PCB. If possible I wanted to use an ATMEGA-328P AU (Arduino nano/uno/etc) on my custom jig. The way I could think of to detect shorts, was to have a shift register which goes through all the pins and sets them to high (5V) one at a time, then the arduino will check the voltage on all the other nets which should be zero unless they are shorted.
I'm just not sure how the "input" on the arduino acts ... is it a high impedance input? I couldn't find any data sheet / info about that. The problem is that if the input is not high impedance, then capacitors that are placed between certain nets, can be reverse charged and reverse 5v will definitely blow a polar capacitor which is obviously not good for a debugging circuit! I thought about other ways, like adding 10k resistors to all the inputs as well as the outputs of the shift register but I'm not sure if that's needed.
Alternatively I can make sure that the nets which have the capacitors, are not reverse polarized, but I would prefer to find a general solution as I will be creating different circuits and not having to change the code every time for different circuits would be great.